Process for treating industrial wastes

ABSTRACT

A process for treating industrial wastes containing sulphuric acid and metal constituents comprising subjecting the wastes to a cell equipped with a plurality of alternately positioned positive and negative aluminum electrodes and charging the electrodes. A solid residue forms which can be further reduced by an ignition step. The aluminum electrodes are one of, or a combination of, rows of pipe, flat plates, or corrugated plates.

United States Patent 1191 Bastacky Aug. 28, 1973 15 PROCESS FOR TREATING INDUSTRIAL 2.272.345 2/1942 Kobe o 159/1310. 1 WASTES 2,292,483 8/1942 Powell l59/DlG. l [76] Inventor: Simon Bastacky, 6604 Dalzell PL, OTHER PUBLICATIONS Pittsburgh, Pa. 15217 Modern Electroplating by Lowenheim pp. 6, published by Electrochemical 800., Inc., (John Wiley NY.) [22] Filed: Mar. 20, 1970 1963.

[211 Appl' 21377 Primary Examiner-F. C. Edmundson 1.1., w. Attorney-Webb, Burden, Robinson and Webb [52] US. Cl ..204/92, 204/93, 204/267 [51] Int. Cl C01g 1/02, C01g 1/10, B01k 3/06 [57] ABSTRACT [58] Field of Search 23/126 200; 851 5 A process for treating industrial wastes containing sulphuric acid and metal constituents comprising subjecting the wastes to a cell equipped with a plurality of a1- [56] References Cited temately positioned positive and negative aluminum ,UNITED STATES PATENTS electrodes and charging the electrodes. A solid residue 1,348,462 8/1920 Weaver et aLL'. 23/200 forms which can be further reduced by an ignition step. 2,005,120 3 Whetzel et a1 t 23/126 The aluminum electrodes are one of, 01a combination 2,143,805 1/1939 Smith 23/126 of rows f pipe, flat plates, or corrugated p|ates 1,308,040 7/1919 Chubb l59/D1G. l 2,202,414 5/1940 Barnes et 23/200 X 7 Claims, 4 Drawing Figures f F W llll 1| I! Patented Aug..28, 1973 Fig. 2

Fig.

Fig 5 I INVENTOR.

SIMON 'BASTACKY mw miww pollution of our water resources. A major pollutant of our water resources are the industrial wastes which result from employing sulphuric acid to treat ,various products. For example, a concentrated sulphuric acid pickle-bath for steel processing soon loses its effectiveness and must be continually replaced andlor replenished with fresh acid. The used acid, termed spent pickle liquor is directly or indirectly disposed of in our streams, rivers, and lakes.

Various forms of evaporators, condensators, diluters,

.and neutralizers have been employed on these industrial wastes, but the effectiveness of these processes is, at best, minimal for the pollution continues at a record pace.

My invention eliminates'this aspect of pollution of ourfwater resources by reducing the wastes to a solid residue. My invention employs simple, yet efficient means for reducing these wastes to'a solid residue. My invention also permits the reclamation of a metal where a metal was removed in the industrial process. My invention is amenable to a batch-type operation or a continuous-type operation, whichever is preferred.

' My. invention is a process for treating spent sulphuric acid industrial wastes by a combination of evaporation and electrolysis. The wastes are treated in cells having a plurality of alternately positioned positive and negative aluminum electrodes. The electrodes can be plate form, corrugated sheet form, pipe form or a combination thereof. Direct current is applied and the polarity In the accompanying drawings, I have shown my presently preferred embodiment of my invention inwhich:

FIG. 1 is a plan view of a cell containing flat platealuminum electrodes;

FIG. 2 is a plan view of a cell containing corrugated plate aluminum electrodes;

FIG. 3 is a plan view of a cell containing a plurality of pipes in rows as the aluminum electrodes; and

FIG. 4 is a plan view of a cell containing rows of pipes as the positive aluminum electrodes and corrugated sheets as the negative electrodes.

My. invention has general application to the treatment of industrial waste containing sulphuric acid and specific application to the pickling or cleaning of metals with sulphuric acid. The general application of my invention is in areas such as industrial mine wastes and wood pulp processing wastes wheresulphuricacid is employed or is present. The specific application is in the area of metal processing and, therefore, for purposes of illustration, I will describe the invention in re-' spect of spent pickle liquor, which is the result of pickling steel in sulphuric acid. Such a spent pickle liquor contains as major constituents in general between 5 and 15 percent sulphuric acid, 3 5 percent iron, and the balance primarily water, with other inci-. dental impurities.

I have found that subjecting these spent pickle li- I 'quors to aluminum electrodes results in a combination of evaporation and electrolysis which forms a solid residue, thereby eliminating or altering all the liquid constituents.

My process is carried out in insulated containers referred to as cells. These cells are filled with a spent pickle liquor. A plurality of alternately positioned positive and negative aluminum electrodes are positioned in the cell much in the same way as a storage battery is constructed.

The shape and number of the electrodes are very important in that the process combines both electrolysis and evaporation and, therefore, an increase in surface area of the electrodes increases the overall speed of the process.

Since electrolysis is involved it is necessary to have the positive electrode thicker than the negative elec-. trode, see FIGS. 1 4. These electrodes may be in the form of plates, either flat 2 or corrugated 4 to increase the surface area, see FIGS. 1 and 2, respectively. These electrodes may also be rows of aluminum pipes 6 wherein each row contains a plurality of pipes 6 connected by a metal bar 10, see FIG. 3. These pipes 6, which terminate above the bottom of the cell, increase the amount of evaporation present since the spent pickle liquor engulfed within the pipe rapidly evaporates and is replaced by additional liquid which enters through the bottom of the pipe. These various forms of electrodes can also be used in combination. For example, rows ofaluminum pipes 6 may be used as the positive electrode and a corrugated plate 4 may be used as the negative electrode, see FIG. 4. I

A suitable arrangement to carry out my process is as follows. A group of rubber cases divided into 6 cells each is employed. A plurality of aluminum electrodes are placed in each cell. These electrodes are alternately positioned positive and negative and are connected to a charger which will supply direct current, generally through a rectifier. A normal theoretical cell requires 2 volts, but to allow for the efficiency of the operation, I employ about 2-56 volts per cell or 15 to 20 volts per case. Therefore, a normal 3 phase, 220 volt line will handle about 30 to 36 cases.

To start the process after the case is filled with spent pickle liquor, one merely charges the electrodes. Initially, for gallon cells, 40 to 50 amps per line are required, but as the evaporation and electrolysis takes place and the water is driven off, the amperage can be progressively decreased. An alternative is to merely replenish the depleted spent pickle liquor with additional spent pickle liquor to be processed.

The electrodes build up heat as a resistant heater while, at'the same time, electrolysis is taking place which also adds to the heat input. As the process continues and the liquid components are driven off or broken down, a solid residue of ferrous sulphate forms .in'

the bottom of the case. The residue'continues to accumulate until there is very little visible liquid remaining.

spent pickle liquoi 'normally having about 13 percent 2.8% by weight 45.3% by weight iron as Fqo, Al as Al,O, Sulphuric Anhydride, SO,

Approximately 85 percent by weight of the starting material was removed, so for every I pounds of spent pickle liquor there is pounds of residue.

An additional step can be added to the process and this is ignition of the residue. The residue can be placed in a furnace and ignited to drive off and break down.

further the remaining constituents. The particular sample which was analyzed above was ignited at 750 C and had a further 63 percent loss in weight.

Other samples of residue have been treated at 1,000" F for 1 hour and thereafter at 750 C for 1 hour with the result that 57.8 percent of the starting residue, before ignition, was reclaimed as Fe O Therefore, the ignition step or steps permit the recovery of the iron which was removed in the first instance.

Economically speaking, it may be advantageous to use relatively small cells which can operate at low ampickling'of steel by sulphuric acid can be reduced to a solid ferrous sulphate residue by subjecting the spent pickle liquor to my process in which I employ a plurality of aluminum electrodes which, by a combination of evaporation and electrolysis, reduces the material to a solid residue. This solid residue of ferrous sulphate can be further reduced by an ignition step or steps to reclaim a substantial amount of the metal in the residue.

I claim: r

l. A process for treating spent pickle liquor obtained from the pickling of steel in a sulphuric acid bath comprising subjecting the pickle liquors to a cell equipped with a plurality of alternately positioned positive and negative aluminum electrodes and charging said electrodes with about 2.5volts per cell, whereby the liquid I portion is dissipatedand a ferrous sulphate residue forms.

2. The process of claim 1 including terminating the charging and cooling the ferrous sulphate.

3. The process of claim 1 wherein the aluminum electrodes are one of or a combination of rows of connected pipe, flat plates or corrugated plates.

4. The process of claim 1 including transferring the ferrous sulphate residue to an ignition furnace and igniting the ferrous sulphur residue to further reduce the weight of the residue.

5. The process of claim 1 including reclaiming the Fe as Fe,0,.

6. The process of claim 4 wherein the ferrous sulphate residue is subjected to a temperature of about 750 'C. r

7. The process of claim 6 including directing 40 to 50 amps to each cell and subsequently gradually reducing the amperage as the pickle liquor is'dissipated.

i 8 I i UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION- Patent No. 3, 755, 102 Dated August 28, '1973 Inventor (X) Simon Bastacky It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as' shownbelow:

n-- should be inserted efter --vbe--.

Column 1 Line'34 --i I 6-- Should read.

Claim 7 Column 4 Line 3l --cla.'1m

Signed and sealed this 1st day of January 197L|..

(SEAL) Attest:

EDWARD M.FLET-CHER,JR. RENE D. TEGTl [EYER Attesting Officer- Acting Commissioner of Patents UsCOMM-DCtO876-P69 I u.s. GOVERNMENT rnnmua OFFICE: I. o-gu-ng. I

F OR M PC4050 (1 0-69) 

2. The process of claim 1 including terminating the charging and cooling the ferrous sulphate.
 3. The process of claim 1 wherein the aluminum electrodes are one of or a combination of rows of connected pipe, flat plates or corrugated plates.
 4. The process of claim 1 including transferring the ferrous sulphate residue to an ignition furnace and igniting the ferrous sulphur residue to further reduce the weight of the residue.
 5. The process of claim 1 including reclaiming the Fe as Fe2O3.
 6. The process of claim 4 wherein the ferrous sulphate residue is subjected to a temperature of about 750* C.
 7. The process of claim 6 including directing 40 to 50 amps to each cell and subsequently gradually reducing the amperage as the pickle liquor is dissipated. 